Sq/In for 12" Fi Q's

I’m looking for some suggestions on my next box build. I have designed and constructed many boxes for myself and forum member (for this and other forums), usually based on vender specs, members targets (ie net volume and tuning freq) and sometimes buy the use of winisd.

Right now I have a set of 12” Fi Q’s that I am designing a box for that will be 5 cu/ft net @ 32hz. This is where I need some suggestions. How many sq/in of port should I be targeting?